It works really well. I highly recommend it.  I use it for two 27in Dell monitors. The arms have plenty of reach to put both monitors horizontally side-by-side.  The monitors can rotate and tilt easily, but also hold their position when set. 

I have clamped the mount to the back of my desk and it does not rock in any direction.  

All of the weight bearing parts are metal and sturdy. Assembly was easy and the instructions were clear.  It comes with all of the tools you need to put it together.